The Goniatite Zones of the Namurian

Abstract

Recent work, both published and unpublished, has considerably increased our knowledge of the goniatite succession in the Namurian of western Europe and the various zones and subzones can now be defined more precisely than hitherto. The major divisions of the Namurian of most value are the former “genus zones” each now raised to the status of an age. Names for these divisions were instituted by Bisat (1928), and were redefined by Hudson and Cotton (1943). The various zones and subzones into which the stages are divided are shown on page 2. The zones differ little from those of previous authors: an attempt has been made to give them equal value and, where possible, the zonal indices in any one stage are of the same genus, thus helping to avoid the confusion caused by the choice as zonal indices of forms of different faunal phase. Neither zonal or subzonal indices are constant in their range in their respective divisions—many of them are confined to a faunal band within the subzone, a few extend into a neighbouring division. The following brief notes are based mainly on the faunal succession of the north of England. The published details of the goniatite faunas in Belgium, Holland, Westphalia, and to a certain extent in Silesia show that the succession there is the same. Comparable forms occur elsewhere as in the Pyrenees, North Africa, Novaya Zemlya, Donetz Basin, Indo-China, Siberia, and U.S.A. The boundaries of the Namurian are those decided on at the Heerlen Congress on Carboniferous Stratigraphy (Jongmans and Gothan, 1937).